Perhaps you should try some spelling variations:
quoc lan » quoc ban, nuoc luan, quoc quan
cac quoc » cac nuoc, cac cuoc, cao quoc
su sach » so sach, vu sach
lan anh » van anh, tuan anh
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
so sanh » do sanh
v nang » va nang, vu nang, van nang
anh ve » hanh ve, anh va, anh viet
ve cua » le cua, de cua, te cua
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((su sach) or (so sanh)) v nang ((x hoi) or (o hoi)). hieu va cac quoc lan anh ve cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sanh)) v nang ((x hoi) OR (o hoi)). hieu va cac quoc lan anh ve cua tre.
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (so sanh)) v nang ((x hoi) or (o hoi)). hieu va cac quoc lan anh ve cua tre*.